Ok. So I have never posted anything on a forum before, so I apologize about the writing or novice nature of this post.
To start off with, all of my troubles started out probably like most fish owners, I was "endowed" with two sickly fantail goldfish from the state fair from my wonderful fiance (now wife). Of course I started this journey very simply, and to not bore you with the details, I have ended up almost two years later with a 40 gallon freshwater planted tank with three (well, used to be...) goldfish (one black moor, and two ryukin), two small plecos, and a variety of goldfish "friendly" plants such as amazon sword, banana plant, anubias, and java fern. Until my attempted move cross country from NC to MO (yes I know... most fish don't survive that journey), everything was fine and happy.
I was lucky enough in NC to have naturally clean and stable water with good properties and a ph of 7.0, so water changes consisted of simply using dechlorinated tap water. Unfortunately, here in MO the tap is aweful for both plants and fish with a ph of around 5.5, and a very unstable alkalinity (I used to manage pools for a living so I am not completely ignorant here). I decided to switch to ro/di water and adding chemicals after the fact. I was able to bring 80% water and all the gravel with me on the move and kept the fish in a bubble aerated container dosed with ammonia remover and stress reducer (and yes I starved them for a few days before), so the tank did not de-cycle upon arrival. However, I was forced to start using ro/di water on the first water change rather than gradual.
I am currently using a ro/di unit installed under my sink and have a full setup with float valve and all. I then treat the water with seachem flourish, flourish nitrogen, potassium, phosphorus, acid buffer and alkaline buffer, and equilibrium. My substrate is medium gravel and the plants are either augmented with flourish tabs, or pots of plant substrate. I have been religiously monitoring ammonia, nitrate, nitrite, ph, and KH. My 10 yr old HOB filter failed, and I was forced to buy a cobalt canister filter. I also added 100W HO lighting (running 10 hours a day). This is when things got bad.
I started noticing algae in HUGE quantities and have to scrub walls every day. After some research, I realized that because I'm using ro/di water, plus lots of light, I need to add CO2 to keep everything in balance. I currently do not have enough money to purchase the parts for another month or two, but figured it was not crucial to the fish. I started noticing the fish "gasping" for air at the surface and immediately thought their tank became un-cycled and were gasping because of ammonia. I took readings and everything was at 0ppm and I verified the solution is good and working. Then after my first fish died
((((( and the readings were still 0, I started looking elsewhere. I then discovered that my canister filter was not disturbing the water AT ALL and I feel very stupid. I corrected this problem by modifying the outlet where it was close to the surface. Ok good oxygen, fish behaving normally. I wake up the next morning to another dead fish
(((((. After reading the chemicals, I discover the ph rose to 7.6 so I determined the COD was osmotic shock. All my chemicals from RO/DI was according to the label to be stable, and the KH/GH was great. I know I'm not using a phosphate buffer since I have plants, but does it really deteriorate within a week???? Do I have to re dose the water in between water changes??? Now the third and final fish is almost dead and I am completely at a loss for what to do.... not sure if my information is correct or what I am doing is right. I don't want to get new fish and introduce them into a hostile environment and kill them too! I just don't understand how I could be so great for two years, and then switching to RO/DI water/planted/canister filter could kill them if I followed everyone's advice. PLEASE HELP!